Week 6 Flashcards
What are the two components of the trigeminal nerve?
- Motor root
2. Sensory root
Where does the motor root of the trigeminal nerve arise?
- In the pons
2. Anteromedial to the sensory root
The motor root of the trigeminal nerve is more compact than the sensory root. True or False.
True
How does the motor root of the trigeminal nerve travel to the trigeminal cave?
It passes as a separate structure with the sensory root through the dura to reach the trigeminal cave.
The motor root passes ABOVE the sensory trigeminal ganglion WITHOUT SYNAPSING and through FORAMEN ROTUNDUM. True or False.
False. The motor root passes UNDER the sensory trigeminal ganglion WITHOUT SYNAPSING and through FORAMEN OVALE.
Where does the motor root of the trigeminal nerve unite with the sensory root?
In or just below the foramen ovale.
What does the sensory root of the trigeminal nerve connect with?
Pons and trigeminal ganglion
What does the sensory root of the trigeminal nerve consist of in the trigeminal ganglion?
Central processes of unipolar neurons
What type of ganglion is the trigeminal ganglion?
Sensory
Trigeminal neurons are bipolar. True or False.
False, they are unipolar
What are the characteristics of a unipolar neuron?
- Have just a single axon like process arising from the cell body
- This process divides adjacent to the cell body to form a central process to the CNS and a peripheral process
Where do the peripheral processes bring information to the neurons of the trigeminal ganglion?
From structures supplied by the three divisions of the trigeminal ganglion. (i.e. most of the sensory fibres in the three divisions of the trigeminal are peripheral processes of trigeminal neurons in the trigeminal ganglion)
Which axon does not have their cell body in the trigeminal ganglion? Where are they located instead?
The proprioceptive axons of the muscle of mastication. Instead the cell bodies are located in one of the sensory nuclei of the trigeminal in the pons (mesencephalic nucleus)
What are the three divisions of the mandibular nerve?
- Trunk
- Anterior division
- Posterior division
What does the trunk of the mandibular nerve consist of? (2)
- Meningeal branch
2. Medial pterygoid nerve
What does the meningeal branch pass through? What else passes through this?
Foramen spinosum
Middle meningeal artery
What does the meningeal branch supply? (2)
- Meninges of middle cranial fossa
2. Mastoid air cells.
Where on the trunk of the mandibular nerve does the medial pterygoid nerve arise?
On the posterior surface
What does the medial pterygoid nerve immediately do?
It immediately gives off a branch which inserts into the medial surface of the medial pterygoid muscle.
What does the medial pterygoid nerve have near the origin?
Two tiny branches:
- Tensor palati
- Tensor tympani nerves
What does the tensor palati nerve enter?
Medial surface of tensor palati muscle
What does the tensory tympani nerve enter? What does it supply?
A minute bony canal to supply tensor tympani in wall of middle ear
What are the two branches of the anterior division of the mandibular nerve?
- Nerve supplying muscles of mastication
2. Sensory buccal nerve
The nerves supplying muscles of mastication enters the superficial surface of muscles. True of False.
False, it enters the deep surfaces of muscles
What are the nerves supplying muscles of mastication?
- Masseteric nerve
- 2-3 deep temporal nerves
- Lateral pterygoid nerve
What do branches of the mandibular nerve to all muscles and to medial pterygoid trunk carry?
- Motor fibres (from motor root of trigeminal)
2. Sensory fibres (including proprioceptive)
Where does the sensory buccal nerve pass?
Passes between 2 heads of the lateral pterygoid, then runs medial to tendon of temporalis and coronoid process.
Where does the sensory buccal nerve send it sensory fibres to?
- Cheek
- Buccal mucosa
- Buccal gingiva over mandibular molars
Where does the buccinator get its motor and sensory innervation from?
Motor: Buccal branch of facial nerve
Sensory: Uncertain
What are the three divisions of the posterior division of the mandibular nerve?
- Auriculotemporal
- Lingual
- Inferior alveolar
The posterior division of the mandibular nerve is mostly sensory. What is the exception?
Mylohyoid nerve which is motor
What is the auriculotemporal nerve?
Cutaneous sensory nerve
What is close to the origin of the auriculotemporal nerve?
Otic ganglion
What is the otic ganglion?
Parasympathetic ganglion of the glossopharyngeal nerve, situated just below the foramen ovale
What does the auriculotemporla nerve pick up? Where does it transmit them?
Parasympathetic hitchikers from otic ganglion and transmits them to parotid
What does the lingual nerve fibres originate from?
Chorda tympani
How does the chorda tympani join the lingual nerve?
Fine nerve which approaches the lingual nerve from posterior and joints it at a fairly acute angle
What type of nerve is the inferior alveolar nerve?
Mixed motor and sensory nerve
What does the inferior alveolar nerve give off? Where does it enter after?
Mylohyoid branch at some, before entering mandibular foramen.
What is the inferior alveolar nerve accompanied by?
Inferior alveolar artery and vein
What does the inferior alveolar nerve form after branching in the mandible?
Inferior alveolar plexus
Where do the terminal branches of the inferior alveolar nerve form?
Below the first and second premolars
What are the terminal branches of the inferior alveolar nerve?
- Mental nerve
2. Incisive nerve
What is the mental nerve?
Cutaneous branch of the inferior alveolar
Where does the mental nerve emerge?
From mental foramen deep to orbicularis oris
What are the articular surfaces of the TMJ? (3)
- Of mandible (head of condyle)
- Of temporal bone (mandibular or glenoid fossa, anterior articular tubercle)
- Complete articular disc attached to joint capsule
What does the articular disc divide?
Joint cavity into upper and lower spaces
What are the stabilising structures of the TMJ?
- Joint capsule and lateral ligament
- Post glenoid tubercle
- Stylomandibular ligament
- Sphenomandibular ligament
Where does the joint capsule attach?
Around the edge of the temporal articular surfaces and to the neck of condyle
What does the the join capsule form laterally?
Lateral ligament
Where is the post glenoid tubercle located?
Posterior to mandibular fossa
Posterior to joint, in front of external acoustic meatus
Where is the stylomandibular ligament located?
Styloid process to angle of mandible, derived from parotid capsule
Where is the sphenomandibular ligament located?
Sphenoid to lingula
What is the disc of the TMJ comprised of? Where is it thick and thin?
Fibrocartilage
Think laterally and anteriorly, thick medially and posteriorly
What is the capsule of the TMJ made of?
Collagen except posterosuperior which is collagen and elastin
What are the superior and inferior internal surfaces of the capsule lined with? What is its function?
Synovial membrane. This is a specialised fibrocellular covering which produces synovial fluid of precise viscosity and chemical composition. Synovial membranes are also phagocytic and remove cellular or molecular debris from the joint cavities.
All the linings of the joint compartments including synovial membrane, articular surfaces of the joint and the disc are connective tissue. True or False.
True
What do the condyle and squamous temporal articular surface develop as?
Membrane bones except for head of condyle and articular fossa which develop by endochondral ossification from the specialised cartilage covering these surfaces.
How does the condyle and squamous temporal articular surface differ from articular cartilage?
Because it has a perichondrium like covering and in the case of the cartilage covering/forming the head of the condyle has vascular channels within the cartilage for the first five years or so of life. Cartilage is reduced to fibrocartilage when growth has ceased BUT CAN REACTIVATE.
The TMJ is an atypical synovial joint. True or False.
True
What is an atypical synovial joint?
Moveable joint with synovial membrane in protected locations e.g. lining capsule.
They are atypical because of the type of cartilage covering the ends of the articulating bones.
What are the ends of the bones in most synovial joints covered with?
Hyaline/artocular cartilage.
Where is the petrotympanic fissure?
Posterior to mandibular fossa - just anterior to external acoustic meatus
What emerges from the medial end of the petrotympanic fissure?
Chorda tympani
What type of join is the TMJ?
Ginglymoarthrosis - sliding hinge joint with a number of unusual features
What movements is the TMJ responsible for?
Depression, elevation, protrusion, retrusion, some lateral movement
What does the opening of the jaw involve?
Rotation, sliding forward and a second rotation of head of condyle.
This moves the head of condyle from contact with posterior part of disc to anterior part. Closure reverses this.
What is the forward/down movement limited by?
Posterior attachment of capsule to temporal bone
What does the disc help to control?
Movement and limits trauma during movement
What dos the sensory innervation of the TMJ? (MAD)
via branches of V/3:
- Masseteric
- Auriculotemporal
- Deep temporal nerves
What do the joint capsules, lateral ligament and retro articular tissue contain?
A variety of mechanoreceptors, involved in proprioception - perception of mandibular position and movement
What does the bloody supply to the TMJ? (SAD)
- Superficial temporal
- Ascending pharyngeal
- Deep auricular (branch of maxillary artery)
What is the motor nerve supply to the muscles of mastication?
Branches of the anterior division of the mandibular nerve CNV/3
What is the arterial supply for the nerves of mastication?
From one of the two main terminal branches of the external carotid (superficial temporal artery and/or branches of the maxillary artery)
What is the venous drainage of the muscles of mastication?
Pterygoid venous plexus
What are the two components of the masseter?
Deep and superficial parts
Where odes the masseter extend?
From medial surface of maxillary process of zygomer and anterior zygomatic arch to angle and ramus of mandible
What does the deep part connect to?
Zygomatic arch to coronoid process
What is the arterial supply of the masseter?
Masseteric, facial and transcerse facial arteries
What is the shape of the temporalis muscle?
Fan shaped
What is the temporalis muscle covered with?
Temporalis fascia
Where is the temporalis fascia situated?
Deep to all of - epicranial aponeurosis and orbicularis oculi, superficial temporal vessels, temporal branches of the facial nerve, auriculotemporal nerve
What is the temporalis fascia attached to?
Superior temporal lines and zygomatic arch. Superficial fibres of temporalis attach to fascia
Where does the temporalis muscles arise?
Arises in the temporal fossa and temporalis fascia
What does the temporalis muscles form? Where does this structure insert?
A thick white tendon which passes deep to the zygomatic arch - inserts medial side of coronoid process and upper ramus
What is the shape of the temporalis muscles?
Fan shaped with posterior fibres almost horizontal and inferior fibres vertical.
What are the temporalis muscles supplied by?
Deep temporal branches of maxillary artery with contributions from superficial temporal artery.
What are the two heads the lateral pterygoid? Where do they both insert?
2 heads - smaller, upper head arising infratemporal surface of sphenoid, lower head arising lateral side of lateral pterygoid plate.
They both insert into the neck of condyle of mandible and capsule of TMJ
What are the two heads of the medial pterygoid? Where do both heads go?
2 heads - deep head arises on the medial side of lateral pterygoid plate. Superficial head (initially lateral to lateral pterygoid) - arises pyramidal process of palatine bone (anterior to pterygoid fossa).
Both heads go to medial surface of ramus
Where is the maxillary artery in relation to the lateral pterygoid?
Superficial (55 - 70%) or deep (30 - 45%) to lower head of lateral pterygoid, then between two heads into pterygopalatine fossa
What nerve passes between the two heads of the pterygoids?
Buccal
What is lateral to the lateral pterygoid?
Tendon of temporalis
What is medial to lateral pterygoid?
Middle meningeal artery, sphenomandibular ligament, chorda tympani
Where passes between the lower border of the lateral pterygoid?
Inferior alveolar nerve and artery and lingual nerve
What is lateral to the medial pterygoid?
Inferior alveolar artery and nerve
What is medial to the medial pterygoid?
- Tensor palati
- Styloglossus
- Stylopharyngeus
What is deep to the styloid muscles?
Superior constrictor of pharynx
Where is the buccinator attached?
To the outer surface of the posterior mandible and maxilla and pterygomandibular raphe
Where is the posterior part of the buccinator in relation to the medial pterygoid?
Deep/emdial
Where does the anterior part of the buccinator curve? What happens to the fibres there?
Towards modiolus where fibres cross over and insert into orbicularis oris.
What are the two innervations of the buccinator?
- Buccal branch of facial nerve
2. Long/sensory buccal branch of mandibular nerve
What does the buccal fat pad separate?
Posterior buccinator and pterygomandibular raphe from ramus of mandible and masseter
What can the pterygomandibular raphe attach to?
Hamulus
Where does the superior constrictor of pharynx attach to and where?
Pterygomandibular raphe posteriorly
What are the actions of the muscles on the TMJ?
- Depression - lateral pterygoid, supra and infrahyoid, gravity
- Elevation - temporalis (vertical fibres), masseter, medial pterygoid.
